Season brisket generously with salt and pepper. Add to Dutch oven and brown over high heat, about 5 minutes per side. Place brisket, fat side up, on onion mixture in roasting pan; surround with bones. Add remaining broth mixture and tomatoes to Dutch oven; bring to boil, scraping up browned bits. Pour mixture over brisket.

Scrape fat from top of pan juices; discard fat. Transfer brisket to cutting board, scraping gelled juices off brisket back into roasting pan. Bring contents of roasting pan to simmer. Discard bones. Pour contents of roasting pan into coarse strainer set over large bowl. Press on solids to release as much liquid as possible. Purée solids in processor, using on/off turns. Mix enough purée into juices in bowl to form thick sauce. Add tomato paste and whisk to blend. Pour sauce into medium saucepan and simmer until heated through. Season with salt and pepper.

Vegetables

Bring large pot of salted water to boil. Add all squashes, turnips and carrots and cook until crisp-tender, about 6 minutes. Using slotted spoon, transfer to large bowl. Add potatoes to boiling water and cook until just tender, about 12 minutes. Using slotted spoon, transfer potatoes to same bowl. Add onions to boiling water and cook until almost tender, about 4 minutes. Drain and cool slightly. Peel onions; add to same bowl.

Assembly

Meanwhile, boil margarine, honey and thyme in heavy large skillet over high heat until syrup is reduced to 1/3 cup, stirring often, about 5 minutes. Add cooked vegetables, tomatoes and asparagus; toss until heated, about 5 minutes. Season with salt and pepper.